''The $64,000 Challenge'' - Misc episode 1
I'm sure someone will determine the date soon. "The $64,000 Question" was one of a handful of rigged game shows, so I presume this spin-off series was rigged too. But it does feature Gloria Lockerman, which gives it some historical interest.
Run time 29:18Audio/Visual sound, black and white
February 28, 2017
So I did a bit of digging... (airdate found)
One commercial mentions "a great gift for Mother's Day", which was May 13 in 1956 (Sonny Fox, the original host, remained through the end of August '56).
The Spelling game (Gloria Lockerman vs. Andy Douglas) is the most important, though, as per the above article (which quotes newspapers dated June 5 and 10, 1956) they ended up tying all the way through the $64,000 top prize level, but rather than do another game the show opted to give each of them $32,000.
As such, I'm pretty sure this episode aired May 6, 1956.